Hi! Thank you for the quick response. Yeah, I already registered a channel with ThingSpeak, and I’ve put the stuff for that into lines 201-206 (the stuff in the sketch above is just placeholders), and running it with those keys and ID’s still doesn’t work. I’d wondered if mqtt.thingspeak.com had been changed to a different URL recently. Is there anything in ThingSpeakPublisher.cpp or ThingSpeakPublisher.h that I need to change?